Introduction; Required Tools - Garmin GNC 420 Maintenance Manual

DISASSEMBLY AND ASSEMBLY
4.1

INTRODUCTION

Repairing the unit is accomplished by removing and replacing defective boards.
disassemble and reassemble the unit in order to access the boards, look at the assembly drawings
in Section 7 and the parts lists in Section 6.
Each unit in the 400 Series contains static sensitive components.
Observe proper anti-static procedures when testing the unit.
Do not replace assemblies with the unit turned on. Hazardous
voltages exist on the Inverter Board (Figure 7-2, Item
012-00256-00).
voltages range up to 2500 V ac peak to peak. Under open
circuit conditions voltages can range over 8000 V ac peak to
peak. Remove all power to the unit and wait at least six
minutes before starting disassembly. Death or serious injury
could result from electrical shock.
4.2

REQUIRED TOOLS

Standard shop equipment can be used to remove and replace defective boards.
The 400 Series lens is coated with a special anti-reflective
coating which is very sensitive to skin oils, waxes and abrasive
cleaners.
HARM THE ANTI-REFLECTIVE COATING.
important to clean the lens using an eyeglass lens cleaner which
is specified as safe for anti-reflective coatings and a clean, lint-
free cloth.
400 SERIES MAINTENANCE MANUAL
P/N 190-00140-05
SECTION 4
Under normal operating conditions the
CLEANERS CONTAINING AMMONIA WILL
To help
It is very
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